The child (not pictured here) has been placed with youth services
Authorities in Bavaria, southern Germany, have taken a seven-month-old boy into care after his parents offered him for sale on eBay "as a joke".
The unnamed child was advertised as a "nearly-new baby" with a starting price of one euro (£0.80, $1.6).
Police have launched an investigation into possible child-trafficking by the infant's father, 24, and mother, 23.
The mother told a German newspaper: "It was only a joke. I just wanted to see if someone would make an offer."
Speaking to Bild, she said she was also being made to undergo psychiatric tests.
'Gotten too loud'
A police spokesperson in the Bavarian town of Krumbach said the mother had also told police the offer had been a "joke".
"That's not yet clear," the spokesperson added.
"Detectives are investigating on suspicion of child-trafficking."
Police were alerted by a number of internet users across Germany who had seen the offer in the auction website.
According to the police, the posting read:
"Offering my nearly new baby for sale, as it has gotten too loud. It is a male baby, nearly 28in (70cm) long and can be used either in a baby carrier or a stroller."
No offers were made for the child in the two hours the advert was showing, police said.
EBay deleted it but assisted police in tracking down the parents, the Associated Press adds.